Telephone-exchange system



ci. DEAKlN Er AL.

TELEPHONE EXCHANGE SYSTEM Filed Oct. 16, 1923 2 Sheets-Sheet l ln ver: fans- Gara/al' Denk/M LS'UMZ G. 13E/MUN ET AL TELEPHONE EXCHANGE SYSTEM Filed oct. 16, 1925 2 sheets-sheet 2 Dem., 219, T1925 Patented Dec. 29, 1925.

l lUNITED s'rATr-:s

PATENT OFFICE..

GERALD IEAKIN .AND IIPA `PO`LINKOWSKY, OF ANTWERP, BELGIUM, ASSIG-NORS T0 `WESTERN ELECTRIC CQMPANY, INCORPORATED, O'FNEW YORK, N. Y., A CORFORA- TELEPHONEPEXCHANGE SYSTEM.

.application filed .october 16, 192s. serial No. 668,806.

in Winch :preference is given to toll calls over'local calls.`

In systems of this lrcharacter, it is usual to arrange that :upon .a Itoll call bein `received for a subscriber who is already usy in a local connection, ,either as a calling or a called subscriber, .the Aconnection `previously established 'With ya local subscriber may be broken down and the toll connection extended kto the local fsubscribers line. `Diliculties are met with when applying a system of this character to `a rlvate "branch exchange group of 'lines as l1t is usual to arrange A.that lche Ifinal selector .switches for establishing toll connections lrunt over those primate branch exchange lines which are busy either b in 'local or ltol-1 connections in an endeavor to lind pa lline which Ais entirely free.. ln doing this, the nal selector switch may moi/'e over all the lines of ithe private ex change group and :will come to restin c011- nection'W-itli Ithe linal line therein, but if the line .is busy in ,a toll connection, it is not disturbed. As a result, Athe toll connection may not be `.extended 'to the private branch exchange although `a .number vof the lines of the Igroup extending thereto may be occupied on'ly in local calls.

lt is `therefore an object ,of this Ainvention to provide an improved system of this character which will obviate the disady'antage referred to.

"In the :terminal bank group or groups of iinal selectors provided `for operating to select an V,idle one of a group of private branch exchange lines, the lines of :the group, with the exception of the last are dilfereutiated from .tflielastlne .ofthe group and priva-.te or ordinary subscribers lines, by the fact that the cutoff relays and message register magnets which are `connected iu parallel to .the sleeve terminals of the lines are not shunted by a .resistance element. When., therefore, .a fma'l selector tests the terminal of .a trunk line in a group that 1s busy, if it is other than the ,last line, `the .test potential will be suoli as to prevent the .energization of the private branch exchange relay of tli'e .selector and., consequent-ly, the selector brushes Will be ladvanced to the terminal of the next line. If .the selector is thus advanced over terminals of busy lines .until its "brushes rest on the terminals of the last line of `the group, then `due .to the additional shunting resistance, the busy potential encounteredfby the test brush of the lselector w'll :be greater and the private branch .exchange test .relay of the selector will energize to .arrest the brushes of vthe selector .upon .the terminals :of the last luie of the grou The object .of ,this invent-ion 1s realized by .arranging that :upon a line `.of a private .ranch .exchange group of .lines being `taken into .use for a .toll connection, the line immedia-tely preceding this line in the group thereupon becomes marked .as a inal line thereof by `libe .connection .of a resistance element Vin lshunt of ythe usual cutoff .relay and message register magnet. When this latter line is taken :into luse in `a toll connection, the line immediately preceding it is caused also to .test as `the final line in the group. This operation .may be extended over all or part of the .lines of the group and `in this manner .hunting is prevented `beyond the line immediately preceding the line of the group which is the last to be :engaged in a toll eonnection.

,Referring to the accompanying drawings, Fig. l shows .a iinal selector of the type which .may beemployed in a full mechanical system tto extend local connections to direct subscribers lines or lines-of a privatebranch excl'range group or may be employed by the toll operator to extend toll connections to such lines. The brushes of a second final selector of the same type are also indicated at 199.

Fig. 2 shows schematically a group l of private branch exchange lines terminating in the bank of a final selector 150 through which toll connections may be extended, and also terminating in the bank of a final selector 199 through which only local connections Inay be extended.-

Ithas notbeen considered necessary to disclose herein all of the circuits essential to the establishment of either local or toll connections, and therefore, only the final selector has been illustrated. For a full disclosure of an automatic system of the type vto which this invention is'. applicable, reference may be had to the patent to Lipa Polinkowsky No. 1,381,431, issued June14, 1921. In the following description, it will first be assumed that the first four Ilines of the private branch exchange group shown in Fig. 2 are occupied `in local calls established over the brushes of final selectors such as 199 having access to the lower group of multiple terrninals shown at the left of Fig. 2. It will be further assumed that the last line of the group is idle and that a toll connection is to be established'. to the. branch exchangeo'ver the final selector switch'150 disclosed in Fig. 1. The desired toll connection is errv tendedto thetrunk terminals of the idle linalselector 150 in theumanner fully set forth Vin the aforementioned patent. Y As soon as the final selector is'taken for use, the fundamental circuit `is closed at the sender, relay 1 72 is energized andy sequence switch 100 is advanced into position 2, over a circuit extending from the armature and front; contact of relay 17 2, through the contact of cam 102. wWith sequencepswitc'h 100 .4 in position 2, the operation of .theftripping spindle 173 takes place, the `circuit therefor including the lower contact of vcam 103 and ythefronI contact and armature of relay172.` The interrupter 174 of suchv trip`v ping spindle places the usual intermittent shunt upon the portion of the fundamental; circuit extending to 'the sender overV the lower contact of cam'105. .Upon the completion of the operation ofvtripping spindle 173, to causev it-to release the desired set of brushes in 'the subsequentl operation of the brushcarriage, relay 172 becomes deenergized an'dsequence switch 100 is moved out of its second position into its `fifth position.

Beforel the sequence switch 100 reaches its fifth position, the fundamental circuit is again closed at the sender in the usual man. nerl and relay 172 being energized over the fundamental circuit, the movement of the brush carriage will take place in the fifth positionof the sequence switch due to the energization of the brush carriage magnet 177 over the contact of cam 110 and the armature and front contact of relay 172. During the operation .of magnet 177, and 'the rotation of the brush carriage, the interrupter 17 8 intermittently shunts the fundamental circuit with the exception of relay 172 in the usual manner. The selected set of brushes having been tripped and brought in this manner to the terminals of the first line of the'desired private branch exchange group, the numerical designation indicated by the operator upon lthe number keys of her sender being the vdesignat-ion of the first line in the y group, the fundamental circuit will be again opened at the sender. Relay 17 2 thereupon deenergizes to stop the movement of the brush -carriage and to close a circuit over the upper contact of cam 104, to drive the sequence switch 100 into its sixth position.

, With sequence switchl 100 in posit-ion 6, and the brushes of the final selector resting on the terminals 208, 209 and 210, ofthe first linev ofthe desired branch exchange, a circuit is' established from battery, through the cut-off relay 211y and lthe message register magnety of this line in parallel, test terminal 210, vbrush 133, winding of relay 196, lower contact of cam 104to ground at the back contact of relay -17 2. Since as previously assumed, thisline isbusy, the potentiall on the test terminal 210 will be such as to prevent lthe energizationf'of relay 196, and consequently, relay 180 is not energized. A circuit isl 'therefore effective for the carriage magnet 177 traceableover the lower Vcontact ofte'am 119, .the back contact of relay 180, to ground at the cont-act of cam 124, and 'the selected brush set is advanced to the terminals of thenext line in the branch exchange group. If this line is also busy, the ff brush carriage continues in motion.

As soon, however, as the brushes of the final selector come into contact withan idle branch exchange line, in the case assumed, the last line of the group, relayV 196 .will be energizeddue to the increased potential on the test terminal 200 resulting from the con-.

nection of resistance 204 in shunt of the cutoff relay 202 and message register magnet 203 whether such line is busy or idle. The

circuit', of relayf196 extends from ground tor of the next preceding line of the group.`

At its right armature and front contact, re-.

vline'iis eneay 'ed in a ytoll connection and relay 201 remains energized, the next lto the last line is made .the 'temporary last line ot ,the group.

At the final selector 150, upon .the energization of ,relay 196, a `circuit is established floln battery .over the armature and contact of relay196, the winding of relay 180, to

:groiuidat the Contact of ca m 123, whereupon Vinlay 180 energizes, opening the circuit ot' the carriage magnet `17.7 and at .its front contact closing a circuit from ground at cam y15241over the upper `contact .ot cam 111 `for drivingl sequence switch 100 `out ot position- 6 into position 9. While passing through position 7, Since thecall Vhas been initiated at la tollv operators'position, ground potential will be applied in the manner set forth in the aforesaid patent to the ring conductor ot the linal selector trunk and .over the contact of tcam 106, through the left winding l.of rela-y 172. Relay 17 2thereupon energizes, closing a circuit for the right winding of re- ,lay185 over thelower contact of cam 108.

Relay 185 .fenergif/es closing a locking circuit for itse'lt over its lett winding and left ar- ,lnatfure `and front contact to .ground at `the front contact oi Vrelay 1.71, which latter relay is maintained energized from the time the :iifnal selector is seized until it is finally reileased. The energizationof relay 185 at `this time .-,ditferentiates'the operation of the final selector as establishing a toll connection. Had 4the tina'l selector .been used in a local connection, relay 185 would not operate `at this time.

As the sequence switch 100 passes through Yposition .8.. a test Vis made to determine the `b1.1.,syor. .idle condition ot the selected line. .Thiscircuit `is closed vover the testbrush 138, ,the right winding .ofrelay 179 to ground at ,the .contact of cam 121, and as the line has been assumed to be idle relay `179 operates. Relay 179 thereupon locks over its lett winding lthrough the vinding of relay 180 to ground at the contact ot' cam 123, `relay 180 energizing in this locking circuit. Upon the energization of relay 180, a circuit is es tablished from the contact ot' cam4124, the armature and front contact of relay 180 and .the upper Acontact of cam 111, i'or advancing sequence switch 100 out of position S) into position 10, where Vit stops since caa 1241 is `opened and relays 171 and 185 are energized.

circuit .over condenser-S 131 and 132, to the' .tip and ring brushes of the `final selector.

The toll operator may now proceed tocall the `branch exchange by depressing her ringing key, whereupon a circuit is established for relay 172 over the contact ot cam 106. Relay 172 upon energizing, closes a circuit over the contact ot' cam 102, for Aadvancing sequence `switch 100 out of position l0 into .position 16, .relay 172 being maintained e11- ergized after the opening `of sequence switch lcam 106 bya circuit including the front contactiof relay 171, the left armature and front contact of relay 185, the right winding of relay 172the lett windingof relay 188, lower contactfof cam 109, and winding ot' relay 18a to battery. The sequence switch will stop in position 16, however, due `to the opening ot sequence contact 102. The branch exchange is ,then rungdirectly 'from the toll operators position over the direct `metallic connection extending through 'the upper contacts of cams .118 and 116.

Upon the `termination of the conversation, the restoration ot' the apparatus Vused is con- -trolled -by :the toll foperator in the usualmanner. When the group selector preceding the final selector 150 is restored, ground .poten- .tial is .removed from ythe sleeve terminal of .the -trunkiextending tothe final selector` and .relay 171 deenergizes, opening the locking circuit of relay 185 and `closing a circuit over the contact .of cam 118 for advancing seq uenee switch 100 Vinto position 17. If Vthe called Subscriber has not fas -yet restored 'his `receiver-to its ,switchhooln relay 172 .is energized `in posi-tion 17 of the sequence switch over -acircuit including the lower contact of ca1n`112, thesubscribe1"s line loop, the upper contact of Cam 113, to ground through the lower contact of cam 107. As soon as the called lsubscriber restores his receiver, relay 172 ydeenergizes closing a circuit over the .upper contact of cam 10.4, for advancing sequence switch 100 into position 18.

:In position 18, ot sequence switch 100, the `brush carriage of `the final selector is lrestored in the well understood manuel'. and having restored drives sequence switch 100 into its iii-st normal position. The tripping spindle 173 has already been restored, the Sequence switch 103 having closed a circuit 4through the tripping spindle magnet in position 12.

Should a second `toll connection to the branch exchange be initiated during` the time that the first four trunks are busy on local calls, and the last trunk is busy on the previ- `ously .described toll call, the iinal selector used O n the lsecond toll c all will be arrested with its brushes enga-ging the terminals of the next to the last lineV of the group, which line was as already described, made temporarily the last line of the group. IVith the switch brushes stopped on the terminals of this line, a circuit is closed as previously described through the test relay 196 of the inal selector, brush 133, test terminal 213, relay 206, thence in parallel to battery through the windings Vof the cut-oiin relay 214 and message register magnet 215, and resistance 207. Relay 206 upon energizing connects resistance 216 to the sleeve conductor of the. next preceding line rendering it temporarily the last line in the group to the next incoming call.

It will be noted in this connection that relays have been shown corresponding to relays 201 and 206 in series'with the sleeve conductors of the last three lines only of the group, whereby the fourth, fthird and second lines of the group may be successively rendered the last line upon successive toll calls to the branch e exchange. It is, of course, obvious that any number ofthe ylines could be similarly equipped.

The second toll call to the branch exchange will be co-mpleted by a final selector switch similar to switch 150 in the manner abo-ve set orthup to the point where the line isrtested by rela-ys 179 and 180 and since as assumed, the line is busy on a local connection, relay 179 does not energize` and sequence switch .00 therefore stops in position 9. In position 9, relay 184 is intermittently operated over the upper contact of cam 109, through interrupter 127, and at its front contact intermittently closes a buzzer circuit through the winding 129 of the tone coil 137, left armature and front contact of relay 184, interrupter 128, buzzer 131 to battery. Tone current then flows to the toll operators position over the lower contact of cam 107, Winding 130 of the tone coil 137 and the upper Contact of cam 122.

The operator is thereupon apprised of the fact that'the wanted line is busy on a local call. Relay 172 is energized at this time as previously described, whereby sequence switch 100 is advanced out of position 9 into position 10, in which position a connection is Vextended :from the operators position over the upper contact of cam 1.07 'and the lower contact of cam 122 through condensers 131 and 132, to the called line. The. toll operator may now converse with the subscriber and inform him that as his line is desired in connection with a toll call, she is going to break down the established local connection for the purpose ot the toll connection. As the manner in which this is done is not an essential part of the present invention, it will not be described herein, reference being had for a tull description thereof tothe patent hereinbeforey referred to. It the private branch exchange lines are engaged in local calls `to a line whch tests as the final line vof the group for causing the line immediately pre-- ceding said line to thereupon test as a final line of said group. Y

2. In a telephone exchange system, a group of lines extending to a private branch exchange, switching apparatusfforextendinglocal and toll connections to saidv branch 'exchange over said lines, and means operative upon the successive extension of toll connections to the branch exchange when all lines are initially busy in local connections for progressively causing the lines to test as inal lines of the group.

k3. InA a telephoneI exchange system, a group of lines extending to a private branch exchange, switching apparatus for extending local and toll connections to said branch exchange over said lines, and means operative upon the successive extension of toll connections to the branch exchange when all lines are initially busy in local connections for causing the lines to test as nal lines of the group progressively forward from the last line toward the first line.

4. In `a telephone exchange system, local and toll selector switches, a group of lines extending to a private exchange and terminating in the banks of said switches, and means operativeonly upon the extension of connections over said toll selector switches to a line which tests as the final line of the group for causing the line immediately preceding-said line to thereupon test as the final line of said group.

5. In a telephone exchange system, local and toll selector switches, a group of lines extending to a private branch exchange and terminating in the banks of said selector switches, and a relay in series with the sleeve conductor of the Iinal line of the group operative only upon4 the extension of connections to said-final line over said toll selector switches tor changing the potential upon the sleeve, conductor of the line immediately preceding said line to cause said preceding line to test as a final line of said group.

6. Ina telephone exchange system, local and toll selector switches, a group of lines extending to private branch exchange and vterminating in the banks of said switches,

a relay in series with the sleeve conductor iso v of the final line of the group operative only upon the extension of a connection to said final line over said toll selector switches for changing the potential upon the sleeve conduotor of the line immediately preceding said line to cause said preceding line to test as a final line of saidl group, a relay in the sleeve conductor 0I the latter line, and means controlled by said first relay for rendering the second relay operative.

In witness whereof, we hereunto subscribe oui` names this 18th day of September A. D.,

GERALD DEAKIN. LIPA POLINKOWSKY. 

